盐酸土霉素与牛血清白蛋白的相互作用研究

采用同步荧光和紫外吸收光谱法,研究了在pH7.40的Tris-HCl缓冲体系下,盐酸土霉素(Oxytetracycline HCl)与牛血清白蛋白的相互作用,研究表明在正常生理条件下盐酸土霉素对牛血清白蛋白有较强的猝灭作用,根据不同的药物浓度、温度及紫外吸收光谱的变化,判断其猝灭方式可能为静态猝灭,同时考察了不同离子存在条件下盐酸土霉素对BSA荧光猝灭的影响。得出在不同温度下反应的结合常数KD分别为4.167×10-5mol·L-1(25℃)、3.6×10-3mol·L-1(37℃),盐酸土霉素与BSA按1∶1的比例结合;根据反应热力学参数确定了它们之间相互作用的主要形式为疏水作用力;采用同步荧光考察了盐酸土霉素对BSA构象的影响,发现随药物浓度的增大,色氨酸残基的最大发射波长不变,而酪氨酸残基所处环境的疏水性改变,从而导致BSA的构象发生了变化。

Studies on the Interaction of Oxytetracycline HCI with Bovine Serum Albumin

The interaction of oxytetracycline HCl and bovine serum album （BSA） was studied by synchronous fluorescence and ultraviolet absorption spectra in physiological conditions.The oxytetracycline HCl has strongly quenched the fluorescence of bovine serum albumin in natural physiological condition,the quenching mechanism is a static quenching procedure at different temperatures and drug concentration.The binding constants and the number of binding sites between oxytetracycline HCl and BSA were calculated at different temperatures.Furthermore,the enthalpy and entropy changes in the interaction of oxytetracycline HCl and bovine serum album were also obtained by the equations of Stern-Volmer and Lineweaver-Burk.From the thermodynamic parameter,it can be judged that the primary binding power between oxytetracycline HCl and BSA is hydrophobic interaction.Moreover,the synchronous fluorescence spectroscopy was applied to examine the effect of oxytetracycline HCl on the configuration of BSA.The alterative configuration of BSA may be induced by the change of hydrophobic environment of tyrosine.